Automotive vehicles have windshields that are typically attached to the vehicle body with an elastic adhesive. Installation of a windshield generally includes, among other things, applying an adhesive bead to either the portion of the vehicle body serving as the frame for the windshield or, alternatively, to a pretreated ceramic coating strip (the “frit”) of the glass windshield itself. In either case, it is known to apply the adhesive bead using an adhesive gun or other manual or automatic dispensing device having a dispensing nozzle. After the adhesive bead is applied to the vehicle body or the windshield, as the case may be, the windshield is pressed against the vehicle body so that the adhesive bead is compressed between the windshield and the vehicle body. Ultimately, the adhesive cures to become an elastic rubber, which provides a permanent adhesion between the windshield and the vehicle body.
It is preferable for the dispensed adhesive bead to be triangular-shaped before it is compressed because the relatively wide base of the bead provides a substantial contact area between the adhesive bead and the vehicle or windshield, as the case may be. In known systems, as shown in FIGS. 1A-1C, the triangular-shaped bead is dispensed with a nozzle 2 having a triangular-shaped outlet orifice 4 in the sidewall of the nozzle. FIG. 1B shows the nozzle 2 of FIG. 1A being moved along a path shown by the arrow, which causes a triangular-shaped bead of adhesive 8 to be dispensed from the outlet orifice 4 of the nozzle 2.
After the adhesive bead is applied, the windshield is pressed against the vehicle body, thereby compressing the adhesive bead. FIG. 1C shows the nozzle 2 of FIGS. 1A and 1C along with the profile of an adhesive bead 6 dispensed from the nozzle 2 before it is compressed by pressing the windshield against the vehicle body. FIG. 1C also shows adhesive bead 7, which is the adhesive bead 6 after is has been compressed. As illustrated, the applied pressure causes the triangular-shaped adhesive bead to turn into a trapezoid-shaped bead. In the process, the bottom side 9 of the compressed adhesive bead 7 is wider than the bottom side 5 of the uncompressed adhesive bead 6. As a result, the contact area between the bottom side of the adhesive bead and the windshield or vehicle frame increases during installation of the windshield. The inventor has recognized that it is undesirable to expand the contact area of the adhesive bead after application and during installation of the windshield. Among other things, the inventor has recognized that such expansion may lead to possible loose contact between the adhesive bead and the windshield or vehicle frame, as applicable, and, as a result, a weakened bond at the interface of the adhesive bead.
The embodiments described hereinbelow were developed in light of these and other drawbacks associated with known nozzles for dispensing adhesive beads in windshield installation applications.